In the spring of 2000, we went on a cross-country tour to promote the first edition of this book; and to support our talk, Pete and I built a large section of portable straw bale wall. This wall traveled thousands of miles and was subjected to all kinds of abuse, and yet at the end of it all showed very little cracking or damage. This got us thinking about prefabricating plastered bale wall panels. These prefab panels are built and plastered in the controlled conditions of a warehouse or factory. They are then shipped to the building site on a boom truck, which lifts the panels into place on the foundation. The walls are then immediately ready to receive a roof.
Our initial experiments with this method were very encouraging, resulting in a very beautiful and simple-to-install demonstration room at the Toronto Home Show.
Further work on the panelized system has led to drastic reductions in time and material use. The biggest savings is in plastering. Rather than fighting site conditions and gravity, using a three-coat system and lots of labor, the prefab panels are plastered while lying flat on the factory floor. In this way, the full thickness can be poured in one coat (just like making a sidewalk!), which is then easily screeded using the temporary sides of the frame to create a consistent finish. Plaster curing takes place out of the sun and wind in controlled conditions. When prefabricated, bale walls cost much less than commercial stud frame walls, even with shipping and crane time figured in. ^
concrete this slab floor (or any slab floor) uses and about the performance of bales in the moist environment of a concrete slab on-grade. We do not recommend the use of bales in any below-grade applications.
Bales as a frame floor insulation may make the most sense, especially where TjIs™ (wooden I-beams created with pressboard and narrow lumber) or open web joists (narrow lumber joined with steel spacers) can be sized and spaced to accommodate the bales with the least amount
of trimming, cutting, and use of oversized lumber.
While many builders have met the challenges of using bales in ceilings and floors, the availability of other lightweight recycled insulation materials such as cellulose fiber and spun rock wool, means you must carefully weigh the advantages and disadvantages of using bales. Be sure the costs, materials, and risks involved do not exceed those of other materials.
A prefab bale wall factory requires only some basic woodworking tools and a roof overhead. The same concept can be applied by owner-builders, who could create tilt-up wall panels onsite.
Prefab straw bale ... as strange as it sounds, it could be an idea whose time is about to come!
8.9a - e: Prefabricated bale wall panels are assembled in frames with permanent top and bottom plates and temporary sides. Plastered lying flat, they are then moved with a crane or forklift, shipped and assembled on site.
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